Tuning means



April 8, 1952 A; JJAHNCKE 2,592,151

TUNING MEANS Filed June 28, 1950 3 Sheets-Sheet l 29 Fig.1

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INVE/ VTO7 2 32 Alberb fahrccke.

- ATTORNEY A. JAHNCKE TUNING MEANS April 8, 1952 3 Sheets-Sheet 2 Filed June 28, 1950 INVENTOR Alberi jahncke- 4 I 4 4 4 4 4 4 I 4 I I ATTORNEY A. JAHNCKE TUNING MEANS April 8, 1952 5 Sheets-Sheet Filed June 28 1950 INVENTOR Alberb falzzzcke ATTORNEY Patented Apr. 8, 1952 TUNING MEANS Albert Jahncke, Geneva, Switzerland, assignor to Hermann Thorens S. A., Sainte-Croix, Switzerland, a limited liability stack company of Switzerland Application June 28, 1950, Serial No. 170,766 In Switzerland July 8, 1949 Claims.

The modern broadcasting receiver intended for receiving short waves (from to 80 metres) must be provided with a fine adjusting device known as Band spread by the trade people. Several kinds of such devices are used by the designers at the present time; however, none of them give full satisfaction. Indeed, in the devices including an operating mechanism linked to an adjusting element or tuner of the frequency of an oscillating electric circuit by a mechanical connection presenting a great transmission ratio, permitting a small displacement of the movable part of said tuner or adjusting element for a very great displacement of the operating mechanism, the lost motion caused by the spaces between the gear teeth inherent to the mechanical parts of the transmission reach such values that it is practically no longer possible to calibrate with accuracy the transmitting stations of the dial of the receiving set. Certain band spread devices include, in addition to a tuning element, or coarse-adjlisting-element, still a fine-adjustingelement inserted in the oscillating circuit and mechanically connected to an operating mechanism different from that connected to the tuning element. This kind of device must be fitted with devices compelling the operator to bring back always the fine-adjusting-element to an even position before actuating the tuning element. This is in order that the wave lengths actually caught correspond with those indicated on the dial by the index.

An object of the present invention is to provide a controlling device to modify the frequency of an oscillating electric circuit, including at least one coarse-adjusting-element, and at least one fine-adjusting-element, each presenting a movable part displaceable in relation to a fixed part. This device aims at eliminating the mentioned drawbacks by the fact that it includes a single operating element mechanically linked, on the one hand, to the movable part of the fine-adjusting-element by a permanent connection, and, on the other hand, to the movable part of the coarseadjusting-element by means of a coupling device, and by the fact that it presents stopping means defining, when the mechanical connection between the operating element and the said movable part of the coarse-adjusting-element is interrupted, the relative position of the fixed and movable parts of the coarse-adjusting or tuning element.

The attached drawing shows schematically, and by way of example, an embodiment of the device itended for an oscillating circuit the tuning or frequency variation of which is obtained by modification of its capacity.

Fig. 1 is a top view, certain parts being cut away and other parts being partly seen in crosssection.

Fig. 2 is a part lateral view, the wall oi the casing being cut away and certain parts being seen in axial cross-section.

Fig. 3 is a cross-section view taken along line III-III of Fig. 2.

Fig. 4 is a part cross-section view taken along line IVIV of Fig. 1.

Fig. 5 is a cross-section view taken along line V-V of Fig. 1.

Fig. 6 is a detail view.

Figure '7 is a schematic view illustrating the wave band switches or sliding commutators of a well-known type and their connections to the four wave bands of the set, one for the high-frequency stage and one for the oscillator stage.

In the attached drawing, the tuning control comprising the coarse-adjusting and the fine-adjusting elements include variable condensers, but it is clear that a similar controlling device could be used in the case of an oscillating circuit, the frequency variation of which is obtained by variation of its self-induction.

The variable condenser represented by way of example is of the type having armatures provided with cylindrical electrodes or wound electrodes. The capacity modifications are obtained by translation diplacements of a movable armature I in relation to an armature 2 rigidly fixed in a casing it traversed by a shaft 4. The latter is guided in bearings 5 and 6, and carries the movable armature l. The armature l is rigidly fixed on the shaft 4 and carries a finger d engaged in a port n made in one of the walls of the casing parallel to the shaft t. Thus the armature I and shaft 4 are maintained in a fixed angular position by the finger d engaged in the said port n. A return spring 1 tends to keep clear one from another the fixed and movable armatures as shown in Figure 1.

This tuning condenser is intended for insertion in any known oscillating tuning circuit (which is not represented). The casing 3 carries, in addition, an auxiliary casing 23 containing a fine-adjusting condenser. The latter comprises a fixed armature 9 having a cylindrical shape, and a movable armature l0 rigidly fixed on a rod ll subjected to the action of a return spring 29 tending to keep clear one from another the armatures 9 and W, as shown in Figure 1.

A cylinder or drum i2 is freely mounted on the end of the shaft 4. A washer 1' retained in position by a screw 1) and co-operating with a shoulder e of the drum l2 defines the axial position of this drum in relation to the shaft 4, the spring 1 tending to keep this washer r in contact with this shoulder e. This drum I2 is fitted with a radial finger l4, intended to be actuated by a finger i5 fixed at the end of a crank 16 fastened to an axle I 1 arranged perpendicularly to the shaft 4. This axle H is pivoted in relation to the casing 3 by means of balls I8 retained by screws [9 which traverse the walls of the casing 3, see Figures 1 and 3.

The crank [8 further carries a catch 28 at the end of which is articulated the rod ll carrying the movable armature H! of the fine-adjustingcondenser. The spring '29 acting on this rod ll tends to keep the finger l5 in contact with the profile of a cam 2| fastened to an axle 22 parallel 'to the axle H, see Figure 3. This axle 22 d is pivoted in relation to the casing 3 by means of balls l8 and carries a gear wheel 26, in mesh with a cog wheel 24 fastened to a shaft 25 pivoted in one of the walls of the casing 3. This shaft carries an operating pulley 28. In order to close the gaps or spaces between the teeth of the cog wheel 24 and the gear wheel 26, the axle 22 carries a second gear wheel '23 exactly similar to the gear wheel 26 and also in mesh with the cog wheel 24. However, this gear wheel 23 is freely mounted on the axle 22. In addition, a hair pin shaped spring 27 (Fig. 6), of which one of the ends rests on the gear wheel 28 fixed on the shaft 22 and of which the other end acts on the said gear wheel 23, tends to displace angularly the latter so that the teeth of the gear wheels 23 and 26 rest on the faces situated in front of one another of two adjoining teeth of the cog wheel 24. Thus, the usual spaces or gaps between the teeth are entirely eliminated, provided that the torque created by the Spring 12! exceeds that which is to be transmitted and necessary for controlling the variable condensers.

A controlling shaft 38, see Figure 1, situated in line with the shaft 4 is guided in bearings 3| and 32 fastened to a casing s fixed rigidly in relation to the casing 3. One of the ends of this shaft carries a controlling knob 33, while its other end penetrates inside the drum l2 and carries one of the parts of a second coupling device consisting of a part 34 of a plate 61. The second part of said second coupling device consists of radial slots 35a and 35b of dimensions corresponding to those 5 of the part 34 of the plate 61 and made in a closing plate 36 rigidly fixed on a flange l3 of the drum l2, see Figure 5.

This flange I3 comprises notches 31 (Fig. 5) and a notch 45 intended to co-operate with a finger 38 fixed rigidly on a transversal wall 39 of the casing 3 as by screw threads or the like. This finger 38 constitutes, with the said notches 31 and 45, a blocking device or stop for fixing warious angular positions of the drum l2. The flange [3 further carries adjustable stops 4| arranged symmetrically in relation to the notches 31 so that, for each angular position of the drum 12, defined by the finger 38 co-operating with one of the notches 31, one of these adjustable stops is situated in front of a stopping part 48 fixed on the wall 39. These stops 4| co-operating with the said stopping part 40 under the action of the return spring I, define, for each angular position of the drum [2, an axial position of the shaft 4, and thus a well defined or calibrated value of the capacity of the variable condenser I, 2.

For the angular position represented on the drawing and defined by the finger 38 co-operating with the notch 45, the axial position of the shaft 4 is defined by the lug l4 resting on the finger i5, which itself rests on the profile of the cam 2 I.

The controlling device represented on the attached drawing Figures 1 and 4, includes a locking device defining the angular positions of the shaft 38 for which a notch 3! or is situated in front of the finger 38. This device comprises:

1. A disc 42 rigidly fixed on the shaft 38.

2. An elastic support 43 freely mounted on the shaft 38 and of which the angular position is defined by a catch 44 sliding into a port 41 made in one of the walls of the casing s.

3. An indicator drum 48 fixed rigidly on the 'shaft 30. The axial position of the support 43 on the shaft 38 is therefore fixed by the disc 42, on the one hand, and by the indicator 48, on the other hand.

4. A ball engaged in a seat 5| provided in the support 43 and co-operating with drillings 50 made in the disc 42.

The controlling device is further provided with an actuating device intended to actuate a wavelength switch (which is not represented), and of which the positions are plotted and indicated by marks made on the periphery of the drum 48 and appearing through a window 1 and indicating to the operator the wave band corresponding to the angular position of the operating knob 33.

This actuating device comprises a pulley I59 pivoted on a fixed part of the casing s and driven in the angular displacements of the shaft 38 by a finger 52 fastened to the drum 48 and engaged in a drilling 53 of the said pulley. The angular displacement of the shaft 38 is limited by the end walls 54 and 55 of a notch 6| traversed by the finger 5'2 .and made on the support 58 of the bearing 31. These walls 54, 55 define the angular positions of the operating knob 33 corresponding to the short wave bands (001 from 13 metres to 30 metres and 002 from 24 metres to 52 metres) Between these two extreme positions (001 and 002 represented in dotted lines on Fig. 4) are situated two angular positions of the knob 33, one GO corresponding to the long waves (over 800 metres) and the other MO corresponding to the medium waves, from metres to 575 metres. Thus it is these four positions of the operating knob 33 which correspond to four positions of the wave-length switch actuated by the pulley 69.

The working of the above mentioned controlling device is as follows:

When the drum I2 is situated in the angular position represented on the drawing Fig. 1, the actuating of the operating element, such as pulley 28 imparts, by means of the cam 2|. on the one hand, a translation displacement of the movable anmature l--as the latter is mechanically linked to the cam 2| by means of the lug l4 resting on the finger l5 which constitute together the first coupling device-and, on the other hand, a translation displacement of the movable armature l8- since the catch 20 is rigidly fixed on the connecting rod l8 which carries the finger l5. Thus, the actuating of the pulley 28 providesfor the position of the drum [2 defined by the catch 38 engaged in the notch 45-the simultaneous control of the coarse-adjusting-condenser and of the fineadjusting-condenser.

For this angular position of the drum l2, the operating knob 33 can be brought in four different angular positions (GO, MO, 0G1, 002) corresponding to the four wave bands of the set and defined by the value of the self-inductions inserted in the oscillating circuit by a sliding type wave band switch with sets of contacts for each wave band of the set driven by the pulley 69 see Figure 7. These four positions of the knob 33 are defined by the ball 49 co-operating with four different drillings 5B of the disc 42.

The mechanical connections between the pulley" 69 and the wave band switches in the oscillator stage 0 and the high-frequency stage HF, which are well-known to the art, is by a cord or cable a fastened to the pulley and wound several times over its periphery. -One end of the cable a is secured to an end of the sliding contact 0 of the oscillator stage 0 and to an end of the sliding contact member HF of the high-frequency stage, respectively. The cable a loops over idler pulleys g and g A second cable a has one of its respective ends connected to the opposite end of the sliding contact member 0 and its other end connected to the end of the sliding contact member HF opposite to the end thereof connected to cable a Cable or loops over idler pulleys g and g. The contacts 10 p and p of the oscillator stage switch are connected to coils with middle taps O0 00 MO, and GO, making it possible to tune the oscillator stage to provide four ranges of wave lengths. The contact 12 connects these oscillator coils to a mixer tube, such as a pentagrid converter tube 6BE6, which tube connects to the usual known connections, such as a first medium frequency circuit and a low-frequency amplifier tube, not shown.

The high frequency stage switch HF together with the four high frequency transformers OCA, OCA MOA and GOA permit the tuning of the lead in circuit to the same four wave ranges provided in the oscillator stage. The HF stage switch includes contacts L L L and L for each wave range and a contact L connected to the antenna A.

Figure '7 further shows diagrammatically a pair of coupled course tuning condensers C and C and a pair of fine tuning condensers f and I connected in parallel with the condensers C and C One of each of the variable condensers have been previously referred to by their structural parts. For example, by varying the capacitance of condenser C which is connected in parallel to the coils in the oscillator stage 0, the four wave ranges may be covered and the same holds true by varying the capacitance of condenser C connected in parallel to the secondary windings of the high frequency transformers in the high frequency stage HF. Only one coarse tuning condenser with armatures I and 2 is illustrated in Figure l to conserve space, however, it is to be understood that spindle 4 of Figure 4 may support any number of movable capacitor or condenser armatures. Similarly the rod I! carrying the fine tuning condenser armatures 9 and 1D may support the armatures of several condensers, like I and f in the diagram of Figure '7.

As shown on the drawing, for the angular positions GO and MO of the operating knob 33, a pin 5'! situated in front of a stop 58, prohibits an axial displacement of the shaft of a sufficient extent to permit the engagement of the two parts of the second coupling device 3435 connecting this shaft 30 to the drum [2. On the contrary, for the angular positions 0C1 and 002 of the knob 33, the stop 53 is no longer in the way of the pin 51. Thereafter, it is possible for the operator to pull the operating knob 33 against the action of a return spring 59 and thus provide:

1. The engagement of the part 34 of plate 61 in one of the slots 35a or 35b according to whether the controlling knob 33 is in the position 001 or 002 and, therefore, to establish a mechanical connection between the shaft 30 and the drum l2 carried by theshaft l.

2. The axial displacement of the shaft 4 driven in the displacement of the shaft 30 against the action of the spring 1 by some parts 60 of the plate 5'! resting on the front face of the closing plate 36.

3. The clearing of the two parts 38 and 45 from the blocking device of drum I2 in angular position.

4. The clearing of the actuating finger 52 of the drilling 53 from the pulley 69, on the one hand, and from the notch 6! on the other hand.

It should be noted that the whole locking device, with its disc 42 and its elastic support 43 is driven in the axial displacement of the controlling knob 33, the catch 44 sliding into the port 41 fixing the angular position of the support 43 in order to enable the ball 49 to jump from one drilling 54] to another.

Now, if the operator imparts an angular displacement to the operating knob 33 situated in pulled position, the drum I2 is angularly displacedsince the two parts of the second coupling device are in mesh-so that the lug I4 is no longer situated in front of the finger l5 and that the mechanical linking between the operating pulley Z8 and the mobile armature l is interrupted. This knob 33 can be brought into five different angular positions for which, when the operator releases this knob, the fixed part 2 and the movable part i of the variable tuning condenser occupy five different relative positions defined by the adjustable stops il co-operating with the stopping means at. To these five positions correspond, therefore, five spread bands of well defined wave lengths. Indeed, when the operator actuates the operating pulley 28, only the movable part iii of the fine-adjusting-condenser is actuated since the mechanical linking :between the cam 2| and the movable armature l is interrupted.

From the foregoing and in examining the attached drawing, it is seen that, when the pin 5'! is situated in front of the edge 62, see Figure 4, of the stop 58, the operating knob 33 is in the position 0C1 so that the wave-length switch is in a position for which it inserts in the oscillating circuit a self-induction of such value that the capacity variation of the Variable condensers enable the adjustment of the said circuit to wave length from 13 to 30 metres approximately. It is, therefore, easy to provide three angular positions of the controlling knob 33 for which the adjustable stops 4| define with the stopping means 50 capacities of the tuning condenser such that the oscillating circuit be adjusted on the smallest wave lengths of the l3, l6 and 19 metres bands. The actuating of the fine-adjusting-condenser bymeans of the operating element or pulley 23 then enables covering the whole range of the wave lengths of the 13 metres, 16 metres and 19 metres bands.

Similarly, when the pin 51 escapes from the edge 63 of the stop 58 the wave-length switch is in the position 0C2 for which it inserts in the oscillating circuit a self-induction of value such that the capacity variation of the variable tuning condenser enables to adjust the oscillating circuit to the whole range of the wave lengths from 24 metres to 52 metres. For this position 002 of the wave-length switch, the knob 33 can be brought in the two angular positions for which the adjustable stops 4| define with the stop element 40 the smallest wave lengths of the 25 metres and 31 metres bands.

As represented on the drawing, the support 56 and the pulley 69 have drillings 68 corresponding to the five angular positions of the controlling knob 33 corresponding to the five spread bands. These drillings give passage to the finger 52 which locks the pulley 69 in its angular position and forbids, therefore, an untimely operation of the wave length switch.

The operating pulley 28 is constituted, in the embodiment represented by way of example on the drawing, by an operating pulley or drum of a cable actuating an index (which is not represented) moving in front of a dial. This cable also connects this pulley to an actuating device which is not represented; but it is clear that these design details can be so replaced by their equivalents and be adapted to the various requirements which may be imposed.

It goes without saying that the controlling device described can be used for controlling the self-induction variation of an oscillating circuit. Indeed, it is sufficient for this purpose to replace the condensers by self-inductions having an axially displaceable core. One could also use as coarse-adjusting-element a variable condenser, and as fine-adjusting-element a self-induction with a displaceable core or vice versa.

In an alternative embodiment, the cam 2| could be replaced by any other actuating means. However, the construction shown by the drawing offers the great advantage of including a spring 2? which suppresses automatically the lost motion errors which can exist in the chain of elements connecting the shaft 22 to the movable armatures l and 10, so that, for a given relative axial position of the fixed and movable armatures, correspond always a same angular position of this shaft 22, irrespective of the armatures position being reached by increasing or reducing the capacity.

This feature of the described device enables a very accurate adjustment of the frequency of the oscillating circuit.

I claim:

1. A controlling device permitting precision tuning to the frequency of an electric circuit comprising at least one coarse-adjusting element and at least one fine-adjusting element, each element having a movable part displaceable in relation to a fixed part, a single operating means, said means comprising drive and driven elements mechanically linked to the movable part of said fine adjusting element by a permanent connection with said driven elements, an additional mechanical connection to the movable part of said coarse-adjusting element driven by a takeoff connection from said driven elements of said first means, and stop means defining the relative position of the fixed and movable parts of said coarse-adjusting element when the mechanical connection between said operating means and the said movable part of said coarse-adjusting element is rendered ineffective.

2. A control for precision tuning to the frequency of an electric circuit comprising at least one coarse tuner and at least one fine tuner, each tuner having a movable part displaceable in rela on to a fixed part, a single fine tuner control means, said control means being constantly corrnected to the movable part of said fine tuner by a mechanical connection including drive and driven elements, a second control means disconnectably coupled to the movable part of said coarse tuner, including an additional mechanical connection, an angularly displaceable driven element disconnectable with said additional mechanical connection as each wave band is selected, an axially displaceable shaft carrying said angularly displaceable driven element connected to the movable part of said coarse tuner, said fine tuner being permanently connected to said drive elements, to thereby continue connection with the movable part of said fine tuner independently of the movable part of said coarse tuner after disconnection thereof from said additional mechanical connection, and stopping members controlling the relative position of the fixed and movable parts of the coarse tuner when the same is disconnected.

3. A frequency. tuning device for oscillator circuits comprising a frame, a single control element exterior of the frame for actuating a coarse and a fine tuning means each tuning means comprising a movable and a fixed part, said single control element being fixed to the end of a shaft journalled in the frame and extending into the frame, a drive gear fixed to the end of the shaft, a set of superimposed driven gears in mesh with said shaft gear, one of said last-mentioned driven gears being yieldably displaceable angularly with respect to said other driven gear to eliminate gaps between the intermeshing teeth of the respective drive and driven gears, said driven gears being fixed to a second shaft rotatable in the said frame, motion imparting means fixed to said second shaft and rotatable therewith, a third shaft rotatable in said frame substantially parallel to said second shaft, means extending from an end of said third shaft, catch means extending to one side of the frame connected to the movable part of said fine tuning means, follower means carried by said third shaft means. engageable with said motion imparting means of said second shaft, finger means carried by the movable part of said coarse tuning means and projecting into the path of movement of said follower means engaged by the said motion imparting means adapted to move the movable part of said coarse tuning means, said follower means and said finger means being disengageable by a manually actuated member to thereby disconnect said coarse tuning means and stop members for retaining the movable part of said coarse tuning means in an indicated set position when said coarse tuning means is disconnected.

4. A frequency tuning device having a coarse and a fine tuner comprising a drum, a control pulley, a cam driven by a shaft and gears connected to the pulley shaft, a cam follower, a lug resting on said cam follower carried by said drum, a connecting means carrying said follower, said connecting means being rigidly fixed to a first catch, a rod coupled to said catch, a notched flange in said drum, a second catch engageable in the notch of the said flange, whereby turning of said pulley simultaneously controls the tuning of said coarse and fine tuners, a control knob connecting a switch movable to a range of different wave bands while said drum is held by said second catch against angular displacement to thereby retain said coarse tuner in operative connection with said control pulley, an axially movable shaft connected to said control knob, a

slotted plate secured to said notched drum flange, a second plate element on the free end of said control knob shaft insertable in the slots in said slotted plate according to the angular displacement of said drum and the relative position of the wave band switch for such angular position, said drum being axially coupled to the movable part of said coarse tuner and axially movable so as to displace said lug from said follower to thereby disconnect said coarse tuner from the influence of said operating pulley, said drum being released from angular displacement by such axial movement and disconnection of said second catch from the said notched drum flange, whereby turning of said control knob permit said wave band switch to be moved to higher frequency wave bands and turning of said operating pulley controls the displacement of the movable part of the fine tuner independently of said coarse tuner,

10 and an indicator drum rigidly fixed to the said control knob shaft adapted to be displaced to give indication of the wave band being tuned,

5. The tuning device as described in claim 4, wherein the wave band control switch connects with a second pulley control turnably mounted in said control knob shaft having a series of radially arranged openings positioned below said indicator drum, and said drum carries a finger parallel to the axis of said knob shaft and movable axially with said shaft into and out of registry with said openings. to thereby retain the pulley and connected Wave band switch in a wave band selected in accordance with the angular position of said indicator drum.

ALBERT J AHNCKE.

No references cited. 

